1. Field of the Invention
The invention relates to mirrors for automotive vehicles. In one aspect, the invention relates to a mirror with a blind zone sub-mirror associated with a recognition enhancement device initiated by the detection of an overtaking vehicle entering the vehicle operator's blind zone. In another aspect, the invention relates to a recognition enhancement device initiated by the detection of an overtaking vehicle entering the vehicle operator's blind zone which induces the operator to monitor the blind zone sub-mirror. In another aspect, the invention relates to a dimming mirror with an automatically dimming blind zone sub-mirror.
2. Description of the Related Art
The operator of a motor vehicle which is being overtaken by a second motor vehicle will typically be unable to observe the position of the overtaking vehicle once that vehicle enters the operator's “blind zone.” A collision between the two vehicles can occur when the vehicle being overtaken moves into the path of the overtaking vehicle because the operator is unaware of the presence of the overtaking vehicle in the operator's blind zone. Rearview mirrors are thus frequently provided with a small spotter mirror incorporated into the rearview mirror assembly, particularly for use with larger vehicles such as pickup trucks and SUVs. The spotter mirror eliminates much or all of the “blind spot” experienced by a driver using a rearview mirror assembly without the spotter mirror. Typically, the spotter mirror comprises a convex mirror element which is mounted to the outer glass portion of the rearview mirror assembly.
Sensing and signaling devices have also been developed which are capable of detecting the presence of a vehicle in an operator's blind zone and alerting the operator to that vehicle through a visual or audio signal. However, although the operator may be alerted to the presence of the overtaking vehicle, the vehicle will not appear in the rearview mirror of the vehicle being overtaken if it is in the operator's blind zone. Thus, unless the rearview mirror incorporates a spotter mirror, the operator must maintain his or her vehicle's position in the roadway until the overtaking vehicle enters the field of view in the rearview mirror, or the operator must look rearward to determine the position of the overtaking vehicle, thereby taking his or her eyes off the road. Even with a spotter mirror, the driver may fail to utilize the spotter mirror, or may not be sufficiently alerted to the necessity of using the spotter mirror, and a collision may ensue with a vehicle in the operator's blind zone.
Prior art spotter mirrors also suffer from another limitation. Light impinging on the spotter mirror element from behind the vehicle, particularly during nighttime driving, can become distorted and reflected to the driver in such a way that the image from the rearview mirror is distorted or otherwise adversely affected, thereby reducing the effectiveness and safety features of the rearview mirror. Furthermore, the intensity of the light reflected from the spotter mirror element will often compel the operator to direct his or her eyes away from the rearview mirror, further reducing the effectiveness of the rearview mirror.
Rearview mirrors can be provided with an automatically dimming feature which reduces the reflected glare from light, particularly vehicle headlamps. This automatically dimming feature typically comprises a light-reactive electrochromic layer interposed between two mirror glasses to form a sandwich structure. When bright light is detected by the electrochromic layer, the electrochromic layer darkens to dim the mirror. However, a spotter mirror attached to the exterior of the mirror glass will not be affected by the darkening of the electrochromic layer. Thus, the spotter mirror will reflect light from a headlamp to the vehicle operator with no reduction in intensity.